overestimation vs appraisal

overestimation and appraisal both are nouns.

Word	Noun	Adjective	Verb	Adverb
overestimation	Yes	No	No	No
appraisal	Yes	No	No	No

As nouns, appraisal is a hypernym of overestimation; that is, appraisal is a word with a broader meaning than overestimation:

overestimation: an appraisal that is too high
appraisal: a document appraising the value of something (as for insurance or taxation)

Other hypernyms of overestimation include estimate, estimation.

overestimation (noun)	appraisal (noun)
a calculation that results in an estimate that is too high	an expert estimation of the quality, quantity, and other characteristics of someone or something
an appraisal that is too high	the classification of someone or something with respect to its worth
	a document appraising the value of something (as for insurance or taxation)